Cracking the Code: Your Punjab Board Class 12 Chemistry Guess Paper is Here!
Are you a Punjab Board Class 12 student gearing up for your Chemistry exams? Feeling the pressure? We understand! Chemistry can be a challenging subject, and effective preparation is key to scoring high marks. That's why we've meticulously crafted a Punjab Board Class 12 Chemistry Guess Paper, designed to give you the edge you need.
Why a Guess Paper for Punjab Board Class 12 Chemistry?
In the crucial final stages of your exam preparation, a guess paper can be an invaluable tool. Here's why:
- Focused Revision: Our guess paper pinpoints the most important questions and topics likely to appear in the Punjab Board Class 12 Chemistry exam. This allows you to concentrate your revision efforts effectively.
- Exam Pattern Familiarity: It's designed to mirror the Punjab Board exam pattern, helping you get comfortable with the question types and format.
- Boost Confidence: Practicing with a guess paper builds confidence as you tackle questions similar to what you might encounter in the actual exam.
- Time Management: Working through the guess paper within a timed environment helps you improve your time management skills for the exam day.
What's Inside This Punjab Board Class 12 Chemistry Guess Paper?
This HTML guess paper is more than just a set of questions. It's a strategic tool packed with:
- Chapter-wise Important Topics: Highlights key concepts and chapters with high weightage in the Punjab Board Class 12 Chemistry syllabus.
- Likely Questions: A curated set of questions based on previous year papers analysis and expert insights, covering all crucial areas.
- Conceptual and Numerical Focus: Includes both conceptual questions to test your understanding and numerical problems to hone your problem-solving skills.
- HTML Format for Easy Access: Delivered in HTML, this guess paper is easily accessible on any device - your computer, tablet, or smartphone. No special software required!
How to Use This Guess Paper Effectively
- Download and Review: Download this HTML guess paper and carefully review the topics and questions covered.
- Solve Under Exam Conditions: Treat this guess paper as a mock exam. Solve it within a stipulated time frame to simulate the actual exam environment.
- Analyze Your Performance: After solving, honestly evaluate your answers. Identify your weak areas and focus on revising those concepts.
- Refer to Your Textbook and Notes: Use this guess paper in conjunction with your Punjab Board Class 12 Chemistry textbook and class notes for comprehensive preparation.
- Don't Rely Solely on This: Remember, a guess paper is a supplementary tool. Consistent study and thorough syllabus coverage are still paramount.
Important Note: This guess paper is prepared based on analysis and expert opinion to aid your preparation. While we strive for accuracy, it's important to understand that this is a guess paper and not the actual exam paper. Punjab Board sets the final exam paper, and their decision is final. Use this as a valuable practice tool alongside your regular studies.
Ready to Boost Your Punjab Board Class 12 Chemistry Preparation?
Don't wait until the last minute! Start using this Punjab Board Class 12 Chemistry Guess Paper today to sharpen your focus and enhance your chances of scoring high marks.
Download Your Guess Paper Now!We wish you the very best for your Punjab Board Class 12 Chemistry exams! Prepare diligently, stay confident, and ace your exams!
Disclaimer: This guess paper is for educational purposes only and should be used as a supplementary resource for Punjab Board Class 12 Chemistry exam preparation. Please refer to the official Punjab Board syllabus and guidelines for complete and accurate information.
Class 12 Chemistry Sample Paper 2024-25
Time: 3 Hours | Max Marks: 70
Section A: 1 Mark Questions
(Questions 1–10 are MCQs, 11–15 are True-False, and 16–20 are passage-based questions)
Multiple Choice Questions (MCQs)
-
A gas deviates from ideal behavior at high pressure because:
a. The size of molecules becomes negligible.
b. Intermolecular forces become significant.
c. Collisions between molecules are elastic.
d. None of these. -
Which of the following is a primary standard substance used in volumetric analysis?
a. NaOH
b. K₂Cr₂O₇
c. HCl
d. KMnO₄ -
The IUPAC name of the compound [PtCl₂(NH₃)₄]²⁺ is:
a. Tetramminechloroplatinum(IV) ion
b. Tetramminechloroplatinum(II) ion
c. Tetrammineplatinum(IV) ion
d. Tetrammineplatinum(II) ion -
The order of stability of the following carbocations is:
CH₃⁺, CH₃CH₂⁺, (CH₃)₂CH⁺
a. (CH₃)₂CH⁺ > CH₃CH₂⁺ > CH₃⁺
b. CH₃CH₂⁺ > (CH₃)₂CH⁺ > CH₃⁺
c. CH₃⁺ > CH₃CH₂⁺ > (CH₃)₂CH⁺
d. CH₃CH₂⁺ > CH₃⁺ > (CH₃)₂CH⁺ -
Which type of crystal defect is shown by NaCl when some chloride ions are missing from the lattice?
a. Schottky defect
b. Frenkel defect
c. Interstitial defect
d. None of these -
The rate constant of a reaction has the unit mol⁻¹L⁻¹s⁻¹. The order of the reaction is:
a. 0
b. 1
c. 2
d. 3 -
Which of the following compounds gives a positive Fehling’s test?
a. Acetone
b. Benzaldehyde
c. Glucose
d. Toluene -
The process used for the concentration of sulphide ores is:
a. Froth flotation
b. Roasting
c. Electrolysis
d. None of these -
Which gas is released during the reaction of sodium metal with ethanol?
a. Hydrogen
b. Oxygen
c. Carbon dioxide
d. Ethane -
The primary structure of proteins is determined by:
a. Hydrogen bonds
b. Peptide bonds
c. Disulfide bonds
d. Ionic bonds
True/False
(Write True or False for the following statements.)
-
The boiling point of alkanes increases with an increase in molecular mass.
-
At equilibrium, the Gibbs free energy of a reaction is zero.
-
An sp hybrid orbital has 33% s-character.
-
∆G° = −RTlnK indicates that a negative ∆G° corresponds to a non-spontaneous reaction.
-
Transition metals show variable oxidation states due to the availability of d-orbitals.
Passage-Based Questions
Read the passage below and answer questions 16–20.
Passage:
Chemical kinetics deals with the study of the speed or rate of chemical reactions. It helps understand factors like temperature, concentration, and catalysts that influence reaction rates. A catalyst increases the rate of a reaction by providing an alternative pathway with a lower activation energy. The Arrhenius equation is given by k = A e⁻ᵅ₊°/RT, where k is the rate constant, Eₐ is the activation energy, and A is the pre-exponential factor.
-
What is the role of a catalyst in a chemical reaction?
-
Write the Arrhenius equation and explain the meaning of Eₐ.
-
What happens to the rate constant k when the activation energy decreases?
-
State one factor that does not affect the rate of a reaction.
-
If the rate constant doubles when the temperature is increased by 10°C, what is the effect on the reaction rate?
Section B: 2 Marks Questions
Q2. A solution contains 2 g of urea (NH₂CONH₂) in 100 g of water. Calculate the molality of the solution. (Molar mass of urea = 60 g/mol).
OR
The boiling point of a solution containing 1.5 g of benzoic acid in 100 g of benzene is raised by 0.273 K. Calculate the molar mass of benzoic acid. (Kₐ for benzene = 2.53 K kg/mol).
Q3. A metal M forms a chloride with the formula MCl₃. The molar mass of the chloride is 133.5 g/mol. Identify the metal M.
Q4. Define the following terms:
(i) Electrophoresis
(ii) Coagulation
Q5. Write two functions of a salt bridge in an electrochemical cell.
Q6. The rate constant k of a reaction increases from 2.0 × 10⁻³ s⁻¹ to 8.0 × 10⁻³ s⁻¹ when the temperature is increased by 20°C. Calculate the activation energy (Eₐ) for the reaction using the Arrhenius equation.
Q7. Explain:
(i) Why is the enthalpy of adsorption always negative?
(ii) Why does physisorption decrease with an increase in temperature?
Q8. Transition metals form alloys with other metals. Explain why, with an example.
Q9. Write the IUPAC names of the following coordination compounds:
(i) [Co(NH₃)₅Cl]Cl₂
(ii) [Ni(CO)₄]
Q10.
(i) Define the term "coordination number" in coordination compounds.
(ii) What is the coordination number of cobalt in [Co(en)₂Cl₂]⁺?
Q11. How will you convert:
(i) Phenol to 2,4,6-tribromophenol?
(ii) Benzaldehyde to cinnamic acid?
Q12. Write the chemical equations for the following reactions:
(i) Aldol condensation
(ii) Cannizzaro reaction
OR
Explain why carboxylic acids form hydrogen-bonded dimers in the liquid phase.
Q13. Give a reason:
(i) Alkylamines are more basic than ammonia.
(ii) Aniline is less basic than aliphatic amines.
Q14. Write the chemical equations for:
(i) Gabriel phthalimide synthesis
(ii) Hofmann bromamide reaction
Q15. Differentiate between:
(i) Fibrous proteins and globular proteins.
(ii) Homopolysaccharides and heteropolysaccharides.
Section C: 3 Marks Questions
Q16. Three electrolytic cells A, B, and C containing electrolytes of ZnSO₄, AgNO₃, and CuSO₄ respectively, were connected in series. A steady current of 1.5 A was passed through them until 2.16 g of silver was deposited at the cathode of cell B.
(i) How long did the current flow?
(ii) Calculate the mass of copper and zinc deposited in cells C and A, respectively.
(Atomic masses: Zn = 65.3 g/mol, Ag = 108 g/mol, Cu = 63.5 g/mol).
Q17. A radioactive isotope decays following first-order kinetics. Starting with 200 mg of the substance, only 25 mg remains after 10 hours.
(i) Calculate the rate constant for the decay.
(ii) Determine the half-life of the isotope.
(iii) How much of the substance will remain after 15 hours?
Q18. Complete the following reactions:
(i) CH₃CH₂OH \xrightarrow{conc. H₂SO₄}
(ii) C₆H₅COOH + SOCl₂ \xrightarrow{}
(iii) CH₃COCH₃ + NaOH + I₂ \xrightarrow{}
OR
Define and explain the Lucas test to distinguish between primary, secondary, and tertiary alcohols.
Q19. (i) Why are lower aliphatic amines soluble in water?
(ii) Write a test to distinguish between:
- Aromatic primary amines and aliphatic primary amines.
Q20. Explain the following with reasons:
(i) Zinc is not regarded as a transition metal.
(ii) Cr²⁺ is a stronger reducing agent than Fe²⁺.
(iii) Lanthanoids show less variability in oxidation states than actinoids.
Section D: 5 Marks Questions
Q21.
(i) Explain the mechanism of the nucleophilic substitution reaction (Sₒ) with a suitable example. (3 Marks)
(ii) Compare the reactivity of alkyl halides and aryl halides towards nucleophilic substitution reactions. Provide two reasons for the difference. (2 Marks)
OR
(i) Explain the Sₑ mechanism with an example. (3 Marks)
(ii) Why do benzyl halides react faster than alkyl halides in Sₑ reactions? (2 Marks)
Q22.
(i) Write the balanced chemical equations for the following reactions:
a. Sandmeyer reaction
b. Hoffmann bromamide reaction
c. Wurtz reaction
d. Finkelstein reaction
e. Kolbe’s electrolytic reaction (5 Marks)
Q23. (i) What is lanthanoid contraction? (1 Mark)
(ii) Explain the effects of lanthanoid contraction on:
a. Ionic radii of lanthanoids
b. Basicity of lanthanoid hydroxides
(2 Marks)
(iii) Mention two similarities and two differences between lanthanoids and actinoids. (2 Marks)
Q24.
(i) Explain the following processes:
a. Froth flotation method
b. Electrolytic refining of copper
(ii) Describe how Fe³⁺ ions are precipitated as Fe(OH)₃ using NH₄OH in qualitative analysis. (3 Marks + 2 Marks)
Q25.
(i) Write the structure of:
a. 2-Amino-3-hydroxybutanoic acid
b. Adenine
c. Maltose
(ii) How do enzymes act as catalysts in biochemical reactions? Explain with an example. (3 Marks + 2 Marks)
OR
(i) Describe the primary and secondary structure of proteins. (3 Marks)
(ii) Explain why cellulose cannot be digested by humans, but starch can. (2 Marks)
